Process of concentrating oxidized ores and minerals



Patented Sept. 1923.

PATENT Inns 0. GERISTENSEIT, OF SALT LAKE CITY, UTAH.

PROCESS OF CONCENTRATING OXI DIZED ORES AND' mm No Drawing.

To all wlzomz't may concern..-

Be it known that I, NmLsO. CnnIs'ri-m- SEN, a citizen of the United States, residing at Salt Lake. City.'in \the county of Salt Lake and State of Utah; have invented certain new and useful Improved Proceses of Concentrating Oxidized Ores and Minerals,

of which the following is a specification.

My process relates to the concentration of oxidized minerals in ores or mixtures of minerals. As is well known to metallurgists 1 no satisfactory process for the concentration of oxidized ores is known at the presenttime. The ordinary methods of mechanical concentration, such as are successfully used for the concentration of sulphides. do not."

give commercial results on many oxidized ores. The air-froth flotation process which has revolutionized the concentration of sulphide ores has not been found applicable to the oxidized ores. The hopes entertained by some metallurgists that the sulphidizing, or sulphide filming or coating of lead and copper minerals; i. e., changing them-superficially to sulphides, would make possible the treatment of these ores by this process have not been realized. It is thus seen that up to the present time no successful process erals may be concentrated with the same degree of efliciency that has been attained in the concentration of sulphides. 1

The process is applicable to the oxidized ores and minerals as such; i. e., the ores require no preliminary chemical treatment such as superficial alteration to sulphides or sulphide filming or coating.

My process is in general applicable to the concentration of the non-silicateoxidized minerals and the separation of these from quartz (and other silica minerals) and silicate gangu'e minerals and is therefore not generally applicable to ores which. contain no quartz or silicates or in which the percentage of these is so small that theirremoral would not increase the value of the ore sufiiciently' to justify the operation: In

Application filed December 14, 1918. Serial No. 288.675.

the specifications I have called those minerals which may be concentrated by my process i..e., the non-silicate minerals, the

ore-minerals and the others, i. e., quartz and sl-hcate gangue minerals the gangue-minerals. In some cases, however, a modification of my invention may be used in the treatment of the ores containing no siliceous gangue minerals for the preferential separation of the other minerals.

My process makes use of a selective action by which the non-silicate minerals and some of the silicate ore-minerals are concentrated and separated from the quartz and silicate gangue minerals. wThis selective action is more or less preferential with regard to the non-silicate minerals and this preferential action may be utilized with some ores consisting mainly of the non-silicate minerals to separate these minerals by a modification of the process as ordinarily applied to ores containing siliceous gangue material.

My process consists of the following steps:

1. The freeing of the different constituent mineral particles of the ore from each other and their reduction to a suitable size.

2. The selective oiling and selective oilflocculation of the mineral particles to be concentrated, in a pulp made by mixing the comminuted ore with water.

- 3. The levitation of the oil-mineral floccules by the incorporation therewith of fine bubbles of a. suitable gaseous medium, thus foi'ming buoyant oil-mineral-bubble fioccu cs.

4. The separation ofthese oilmineralent minerals and ground to the desired mesh;

the comminuted ore is then mixed'with water toform a pulp; suflicient of a suitable oil or oily compound is added and thoroughly mixed with the pulp in such a manner as to subdivide the oil. into a large number of .relatively ver small particles and to. distribute these t roughou't the pulp. This results in the selective oiling andselective oilflocculation of the minerals to be concentrated. Preferably at the same time that the oil is thus being distributed through the pulpa large number of small air bubbles, or bubbles of other inert gas, are injected into the pulp and thoroughly mixed therewith.

' some of these become incorporated in and at- During the injection of the air bubbles the pulp is thoroughly agitated and mixed. The subdivision of the 011 and injection of the air bubbles and their admixture with the pulp are preferably conducted simultaneousl but the oil may be mixed with the water be ore the addition of the ore or ma be mixed with the pul during the grin ing operation. The res t of the admixture of the fine air bubbles with the pulp is that tached to the oil-mineral floccules and levitate these and render them buoyant, forming an oil-mineral-bubble floccule. After the formation of the oil-mineral-bubble floccule the pulp is allowed to become sufliciently quiescent so that the oil-mineral-bubble fioccules rise to the surface of the ulp. The mass of buoyant oil-mineral-bub le floccules thus formed at the surface of the pulp is then removed, leaving the particles of quartz and silicate gangue minerals in the pulp.

The foregoing is only a general statement of the manner of carrying out the process without reference to the details of each step,

. which are given in the following:

1. F reeinp of the zlz'fi'erent mineral particles and grmdmg of the minerals to be concentmteal to a suitable fineness.-

The proper carrying out of this step is very important. It is obvious that the ore must be crushed to such a size that the different mineral constituents are freed from each other, otherwise no separation could be made. The minerals to be concentrated must also be ground sufliciently fine to be amenable to the process, in most cases to mesh or finer. The fine grinding of the ore must not be done with iron (i. e. iron or steel) grinding parts unless the effect of this grinding is removed before the concentration treatment, as the quartz or silicate gangue-minerals thus .finely ground flocculate with the ore-minerals to be concentrated and the selective action of the oil flocculation is thus destroyed. This effect is morepronounced the finer the grinding, the longer the time of grinding, the softer the grinding media and the harder the gangue mineral. This effect when grinding is done with cast iron balls is more pronounced than with manganoid balls, and if the gangue is most- 1 soft mica, the' effect is relatively slight. That it is'essential that fine grinding of the ore be not done with iron or steel grinding media, unless the effect is removed as later described, is readily seen from the following examples: A siliceous oxidized lead ore containing 65% SiO and 10% lead finely' Th ground in a pebble mill gave a concentrate carrying of the. lead andonly 10% silica. The same ore ground to the same mesh and even to a much coarser mesh, with iron balls gave no concentration whatever,

the wholeof the ore oil-flocculated and there was no selective action. An oxidized copper sandstone ore carrying 12% copper, finely ground i a pebble mill gave a concentrate carrying 9 o of the copper in the ore and assaying 48% copper and 12.5% silica and a tailing asaying only 0.3% Cu. This ore ground to mesh with steel balls gave no concentration whatever, the whole of the ore oil-flocculated and there was no selective action and no separation. The same ore ground in a ball mill for only 15 minutes and to a much coarser mesh gave a concentrate assaying 17 5% copper and 66.4% SiO weighing 60% of the ore, a middling assaying 4.5% Cu, weighing 16% of the ore and a tailing assaying 2.5% Cu weighing 24% of the ore, which shows practically no concentration and gave results which are worthless from a commercial standpoint.

Ores finely ground on' an iron bucking board or in the ordinary iron disk grinder give no concentration whatever as the whole .of the ore oil-flocculates and there is no selective action when treated by my process. In practical operation the fine grinding should preferably be done with a pebble mill unless the effect, of grinding with iron is removed before the treatment as later described. All metallic iron mixed with the ore, from the mining operation, should be preferably removed before fine grinding in order to secure the best results. For laboratory tests the fine grinding should be done in a porcelain pebble mill with quartz pebbles or with a porcelain mortar and pestle. Iron from the coarse crushing should preferably be removed before the fine grinding to secure the best results. The effect on the clean particles of metallic iron and the metallic iron then removed from the pulp with a magnet; upon the addition of the oily agent and shaking the test tube vigorously, all the silica. oil-flocculates and the fioccules areleviated in a manner similar to the nonsilicate minerals. The same result is also secured by the similar treatment of feld-' spar and other silicate gangue minerals. e fine gangue minerals thus treated also oil-flocculate preferentially with regard to the ore-minerals. If the finely ground gangue minerals are shaken with water'in a clean iron pipe for three minutes and then transferredto a test tube and the oily flocculating agent added and the test tube shaken vigorously so as to violently agitate the mixture, all the fine silica oil-flocculates and the floccules are levitated and come to t e surface of the. pulp when the shaking ceases, in a manner similar to the non-silicate minerals. lt' very finely ground Inetellic iron, in any considerable percentage is mixed with finely ground ore. the result is the total oil-flocculationof the ore. If only a very small amount of iron is used the entire mass may not oil-flocculate but the floccules carry more gangue minerals than they otherwise would, the effect being proportional to the amount. of metallic iron in the pulp. A similar effect results when very fine metallic aluminum, copper or lead are added to the ore pulp, but the efiect is not nearly so strong as with iron and is less with. lead than with aluminum or copper. The theory of the. action of these metals is given later. tively slight and of very little importance as compared with the efi'ect of the iron. Quartz and silicate minerals, alone. when finely ground on an iron bucking board or in an iron disc pulverizer. or in a ball (iron or steel balls) mill are entirely oiliocculated and the floccules levitated in a manner similar to the non-silicate minerals. From the foregoing it is seen that it is essential that theiine grinding of ores preparatory to treatment by my process must not be done with metallic grinding media, as this destroys the selective action of my process and prevents the concentration of the ore minerals and their separation from the siliceous gangue minerals. As it. is the object of my process to concentrate the non-silicate. minerals and separate them from the quartz and siliceous gangue minerals in the ore. and since grimling with iron causes the quartz and silicate gangue minerals to oil-fiocculate and levimm in my process in a manner similar to the non-silicate minerals and therefore de stroys the selective action of my process and prevents the separation of these two classes of minerals by my process, it is obvious that the fine grinding of ores to be treated by my process must not be done with iron grinding media, unless the efi'ect of this grinding is removed by a special treatmentv before applying my process. lt is best that the ground ore be not kept long in contact with metallic iron or iron pumps or pipes before being concentrated. as this also tends to destroy the selective action oi my process by causing the quartz and silicate gangue minerals to flocculate in a manner similar to the non-silicate minerals. The effect oi grinding or scouring with metallic iron may be entirely removed by the addition of a very small amount of acid, e. g. H. .S() ,.to the gr und ore and agitating the pulp and This eii'ect is rela-- then entirely neutralizing the acid with lime-stone previous to concentration. Ob viously this could not be done commercially if the ore contained much calcite. The neutralizing should not be done with an alkali, however, asthe ore thus treated will still non-selectively oil-fiocculate to a considerable extent. A theory explaining the effect of the iron is given later. Relatively fine grinding of the minerals to be concentrated is necessary to successful oil-flocculation and concentration. The fineness varies with the mineral, for instance, c-arnotite must be ground to extreme fineness to get a good recovery, while calcite may be much coarser. In general most of the minerals to be flocculated should be 80 mesh or fin'er.

2. T he selective oiling and selective oilflocculatz'on of the minerals to be concentrated.

process. In order that the process operate I successfully, it is essential that this step be. properly carried out.

First-the right kind of oils must be used. Only those oils or oily compounds can be used Which not only selectively oil the nonsilicate (and also the silicate ore minerals) but also bring about the selective-oil-flocculation of these minerals.

The pure volatile or essential oils alone, i. e. Without admixture with other oils'or resins (and exceptin rosin or colophony which is sometimes 0 assed with these oils but is not an essential oil) are useless in my process, as they do not selectively flocculate the non-silicate minerals. The slight fiocculating action shown when a large excess of these oils is used is very probably due to rosin acids remaining in the oil. The

rctined or steam dis-tilled pine oils, terpenes,

turpentines and other related and similar oils must be used in very large excess to show any flocculating efiect. The crude pine oils and turpentines which contain more rosin acids show a slightly greater flocculating effect. Rosin spirits, which contain still more rosin acids, gives fair results. Rosinoils. containing a considerable percentage of rosin acids. give fairly good results. Rosin or colophony, which consists largely of free rosin acids (mainly abietic acid) dissolved in essential oils so that the mixture contains a large percentage of rosin gives fairly good results. To secure the best results, however, it is preferable not to use any of the essential or partially soluble oils in the flocculation medium as they tend to prevent the selective oiling and flocculation of the ore minerals.

The mineral oils alone (i. e. Without admixture with other oils or resins) are useless in my process as they do "not selectively oilflocculate the ore-minerals. When-used in very large excess a slight flocculating effect may be shown, but this is probably due to small amounts of fixed organic oils contained in the mineral oil in the form of dissolved bitumen waxes which contain free fatty acids. By mineral oilsis meant the petroleum oils, shale oils, coal tar oils and creosotes, lignite tar oil, etc. etc.

Rosin dissolved in the mineral oils so that theoily compound or mixture contains a large percentage of rosin gives very good results.

The fixed oils asa class give excellent results. Of the animal oils, the fish oils such as menhaden oil, salmon oil, etc. give excellent results; the liver oils, such as cod liver give good results; the blubber oils such as whale oil give good results. The animal fats such as tallow dissolved in other oils give good results, and the animal waxes such as sperm oil give excellent results. Among the vegetable oils, a large number of drying, semi-drying and non-dryin oils, such as linseed oil, castor oil, olive oi etc., give good results. The vegetable fats such as coeoanut oil and palm oil give good results.

The liquid fatty acids such as oleic ac1d give excellent results. The solid fatty acids such as stearic in solvents which w1ll dissolve a large percentage of the acid give good results.

From the foregoing it is seen that an extremely large number of combinations of oils may be useful in' my process but as will be seen also from the foregoing there is one essential feature in all oils that can be successfully used in my process and that is that the oil or oily compound must contain a proportion of' a fatty acid or rosin acid, either free or combined, or some other analogous compound which acts in a similar manner. It should here be noted, as bearing on the theory later given, that the fatty acids combined with inorganic bases (other than the alkalies) form insoluble metallic soaps and that rosin combines with these bases to form the so-called rosin greases.- It should also be noted that the suitable oils are insoluble in water and also that they break up into minute globules when vigorously shaken with water.

In practice I have secured the best results with oleic acid, menhaden oil, and rosin dissolved in kerosene or one of the coal tar oils. Each ore should. however, be tested to see which oil or oily compound gives the best results in its concentration as some oils give better results with certain ores than do other oils.

The second feature of importance is the amount of oil necessary. The amount of oil necessary to secure certain results is fairly sharply defined. In general up to a certain limit the amount of quartz or silicate gangue material carried up by the floccules is inversely proportional to the amount of oil used. This limit is slightly over 10 per cent (10 to 15 per cent) of the weight of the minerals tobe concentrated. For example, if 20 per cent of the weight of the ore is concentrate, the amount of oil used should ble slightly over 2 per cent of the weight of t e ore.

When only a small proportion of the ore 1s to be concentrated this proportion of oil must usually be increased somewhat. The effect of the varying amount of oil on the percentage of quartz or silicate gangueminerals carried by the floccules is shown in the following examples: An oxidized lead ore carrying 33 per cent non-silicate minerals and 67 per cent quartz gave in each case cited below approximately the same recovery (approximately 95 per cent) of the non-silicate minerals in the concentrates, but with 1% per cent menhaden oil (11} per cent of the weight of the ore) the flocculeconcentrates carried 30 per cent silica; with 2 per cent oil, 25 per cent silica; with 2% per cent oil, 20 per cent silica; with 3 per cent oil, 15 per cent silica; with 3.5 per cent oil. 12 per cent silica; 4 per cent oil, 10 per cent silica; 4% per cent oil, 9- per cent silica. A manganese ore (manganite in a porphyry gangue) carrying 50 per cent manganite and the remainder feldspar, gave approximately a 93 per cent recovery in all the concentrates; but with 2 per cent oil the concentrates carried 20 per cent insoluble; with 3 per cent oil, 14 per cent insoluble; with 4 per cent oil, 10 per cent insoluble; with 5 per cent oil 7.5 per cent insoluble; with 6 per cent oil, 6 per cent insoluble. Tests on oxidized copper ores in sandstone gave similar results. In a general way it may be stated that the best concentration is secured by using a weight of oil equal to between 10 and 15 per cent of the weight of concentrates.

More oil than this gives very little improvement in the grade of concentrates. Considerable more oil may be used without detrimental effect, but if'a very large excess of oil is used the floccules may lose their on the total of the mineral oils or other oils used as solvents plus the active ingredients (such as resin) e. g. in a rosin-kerosene mixture the percentage of oil should be figured on the rosin content alone if the mixture is dilute with regard to the rosin.

The foregoing is of course only a general memes statement of the amount of oil to be used.

- tinctly after being removed from the pulp.

With increasing proportions of oil the floccules become progressively heavier, more discrete, carry fewer fine air bubbles and less siliceous gangue material, and maintain their fiocculate character distinctly after separation from the pulp.

The manner of bringing the oil into contact with the mineral particles is important. The oil must be broken into minute globules in the pulp in order to act well in selectively oiling and oil-fiocculating the ore-minerals. This may be brought about by mixing the oil with the pulp during the grinding operation but is preferably done by a very vigorous mechanical agitation of the oil or oily compound mixed with the pulp containing the comminuted ore. By this operation the particles of the ore minerals are selectively oiled and flocculated; i. e.,brough together in small clinging aggregates. The size of these aggregates will vary with dif ferent minerals and the fineness of grinding. The floccules of the more readily oil-flocculable minerals are usually larger, as large as 1,-" in average diameter, the less readily oil-flocculable minerals which require fine grinding may be much smaller. These aggregates contain the minerals to be concentrated (-i. e.

the ore-minerals) and also practically all the oil added to the pulp (unless some essential or partially soluble oil is used which is not desirable) and a small amount of gangue mineral. The oil may be recovered from the concentrates by suitable methods such as dissolving with suitable solvents and distilling ofi' the solvents, and may be used again in the process. This step of oiling and flocculating'is preferably carried out at the same time that the floccules are levitated; the selective oiling and flocculation and levitation being all carried out in one operation.

3. The levitation. of the oil floccules.

. The levitation of the oil floccules is brought about by the injection of numerous fine gas bubbles (preferably air) into the pulp and thoroughly mixing them therewith. In order to secure good results the bubbles must be relatively very small. Any relatively large bubbles have very little effect in the levitaless injurious after the flocculation.

tion' of the floccules. This levitation may be brought about by mechanically mixing or heating air into the pulp with paddles or by projecting air bubbles through a porous medium into the pulp, or by a combination of these. two methods. The best results are obtained by the mechanical or combined methods as it is difficult to secure fine enough bubbles by passing the gas through any ordinary porous media now used. As previously stated the selective oiling and selective oil-flocculation and the levitation of the oil-floccules are all best brought about in the same operation, preferably by the vigorous mechanical agitation of the pulp in such a manner as to breakup the oil into fine globules and inject numerous fine air bubbles into the pulp and thoroughly mix these and the mineral particles in the pulp. By this operation many fine bubbles become incorporated in and. attached to the oil-mineral floccules, forming a buoyant oil-mineralbubble floccule. If as is preferred the selective oiling, oil-flocculation and levitation are all performed in a single operation, the oil-mineral-bubb'le floccules are formed at once and may be removed as described in the next step. I have found that the machines which give best results are those which furnish the largest supply of the finest bubbles during the operation.

In the foregoing I have made no statement as to the kind of solution in which this process of oil-flocculation should be carried out. This is a vital feature of the process.

In general, my process will not operate successfully with acid or alkaline solutions in the pulp and gives much betterresults when the solution is free from dissolved salts which act as flocculating agents.

Mineral acids, even in a very small amount entirely prevent the oil-flocculation of the ore-minerals. For example, with many ores as little as .025 per cent of free H SQ, .in the solution entirely prevents the oil-flocculation. Most ores contain'sufiicient calcite or other soluble material to neutralize small quantities of acid in the solution, so that in operating the process the solutions must be tested for free acid. If the solution in the pulp is clearly acid to litmus the ore-minerals cannot be successfully oil-flocculated. After the ore-minerals have been completely oil-flocculated the acid de-flocculates them with difiiculty and the acid is therefore mugh T e effect of the acid after oil-flocculation is to cause the oil-mineral-bubble floccules to contract somewhat and become more dense and to lose a part of the air bubbles which makes them more difiicult to levitate and Some ores contain material which will neu- I tralize the NaOH and others have the power of absorbing the NaOH so that it is neces sary to test the solution. If the solution in the pulp is clearly alkaline to litmus paper the ore minerals cannot be oil-flocculated in this solution. The alkali in the pulp may be neutralized with acid and its effect destroyed and the ore-minerals can then be oil-flocculated. If the alkali is added after the oil flocculation, it destroys the levity of the oilmineral-bubble floccules and causes them to sink and with continued agitation deflocculates them. Soap, which is alkaline, even in small quantity also prevents the oil-flocculation and destroys the levity of thefloccules already formed. v

Salts, such as NaCl, which act as ordinary flocculating agents are not so objectionable as the acids or alkalis but it is very much preferable that they be absent. The effect of these salts is to first cause the non-selective oil-flocculation of all the minerals in the pulpsimilar to the metallic iron, but with continued vigorous agitation the oilflocculation becomes more selective and the particles of gangue-minerals are rejected by the floccules. This makes it necessary, in order to secure any concentration with salts in solution that the pulp be subjected to vigorous agitation for a period long enough to make the non-selective oil-flocculation selective before the removal of the concentrates. This is objectionable in any commercial operation, also the concentrates are not so clean as without the salts. It is therefore preferable that no salts be present in the solution. This efl'ect is less pronounced with ores having a small percentage of concentratable minerals than with those having a larger percentage. Common salt in as small a proportion as 04% in the solution will give these effects. The gangue minerals show no oil-flocculation whatever with salt in the pulp unlesssome ore-minerals are also present in the pulp. Salts which are hydrolized in solution give efl'ects intermediate between theacids or alkalis and the neutral salts, the precise eflect depending on the degree of hydrolysis and nature of the ore. Though the ganguefmim erals alone show no oil-flocculation with the salts in solution when the pulp becomes,

quiet the particles of gangue-minerals do flocculate in the ordinary manner and the flocks slowly settle just as in the ordinary naeea surface of the pulp.

and well known process-of flocculation and sedimentation or settling. If the ore-minerals are first oil-flocculated and levitated lation are entirely independent phenomena.

I have used the term flocks in referring 'nomena show that the two kinds of floccuto the product of ordinary flocculation, and

floccule in referring to oil-flocculation in order to distinguish between the two as they are entirely dissimilar in their characteristics.

floccules; the ordinary flocculation is nonselective; the oil-flocculation is selective; the ordinary flocculation is relatively slow; the oil-flocculation is very rapid; the ordinary flocks are easily broken up and dispersed; the oil-floccules are relatively permanent andlnaintain their character well; the ordinary flock is relatively much more dispersed than the oil-floccule and settles much more slowly than the delevitated oil-floccule.

My process is also preferably carried out in relatively dilute pulps; i. e., over six and up to fifteen or more of Water to one of ore. The finer the grinding the more dilute the pulp should be to secure good results. Warm pulps give slightly better results than cold pulps.

My process should also notbe carried out in direct contact with the metal of an iron machine, as good results cannot be secured.

The effect ofthe violent agitation of the oil and pulp with the metallic iron is to oil-flocculate a large more or less destroy the 'mlective action of the process. Slightly better results can also be secured in 'a glass or wooden machine than in a metallic machine, such, for example, as one made of aluminum.

4. The separation; of tke leoitatcd floccules 0r oil-mineral-bubble floccules.

The last step, the separation of the levitated floccules floccules, is brought about by allowing previously agitated pulp to come to a relatively quiescent condition so that the buoyant oil-mineral-bubblc floccules may come to the The mass of buoyant floccules thus formed, may then be skimmed ofi the surface of the water by mechanical means, or allowed to accumulate until they reach a depth sufiicient to cause them to overflow over an edge of the vessel (which The ordinary flocks cannot belev1tate d; the oil-floccules are readily levi-. tated, 1. e., made into oil-mineral-bubble.

part of the fine gangue particles as previously described and to or oil-mineral-bubble' should be very slightly higher than the level of the pulp). Though the. oil-mineralbubble floccules are sufiiciently buoyant to be readily removed in this manner, a slight] better grade of concentrate can be secure if a number.of fine bubbles are injected into the pulp during this part of the recess. If large bubbles are in ected into t e pulp in this stage of the recess they. may serve to drive the levitated floccules over the discharge lip of the apparatus but this action is merelya mechanical means of removing the floccules and has no real relation to the process itself. If many large bubbles occur at this stage of the process it has been found to be disadvantageous rather than helpful as the pulp is thereby kept in constant agitation which interferes with the rising of the floccules and also disturbs the mass of these at the surface by constantly breaking through the mass and keepin it in agitation. Also it is perfectly obv ous that the ore-minerals may first be selectively co ucentrated into oil-mineral-bubble floccules and then be allowed to lose their bubbles and settle as less buoyant oil-mineral floccules and these can then be separated from the remainder of the pulp by any suitable washing or concentrating process and niachinery of the same kind as those now in general use in the ordinary mechanical concentration of sulphide minerals, but this is not a preferred method,'though it can be used and will give good results in many cases.

In the treatment of most ores the concen-- trating operation is preferably divided into two steps. An oil-mineral-bubble flocculeconcentrate is first separated from the remainder of the ore as described. This concentrate is then retreated or cleaned by a similar operation to remove as much more of the gangue material as possible. All the oil used may be added in the first, or roughing operation and the second, or cleaning operation be conducted with the addition of more oil, but it is much preferable in the majoritv'of cases to add most (say three-fourths) of the oil or oily compound in the roughing operation, thus forming relatively lighter floccules, and then add the remainder of the oil in the cleaning operation. forming a heavier floccule. Too light a fioccule should not be made in the roughing operation however, as if this is done entirely too .much siliceous gangue material will be included in the floccules.

The oil-mineral-bubble floccules quickly lose most of the air bubbles when removed from the pulp and dropped into water, and the oil-mineral floccules settle very quickly. These oil-mineral floccules maintain their flocculate character with great persistency when sufiicient oil has been used, and the removal of the excess water from the floccule-concentrates by filtration is accomplished without difliculty no matter how fine the grinding. After the removal of the concentrates and settling in water, some of the fine silica included in the floccules gradually separates out and can be removed by washing if desired.

The process may be carried out in any suitable apparatus which will thoroughly agitate. the pulp in such a manner as to break up the OllilIltO minute globules and inject or beat air into the pulp in fine bubbles and thoroughly mix these with the pulp and thereafter allow the so-treated pulp to remain in a sufficiently quiescent condition 'for along enough period that the levitated floccules come to the surface, so that they can be removed and separated from the remainder of the pulp. Many different types and forms of machines may be used for this purpose and I therefore do not desire to connect the process with any particular machine.

For testing purposes a machine which is intermittent in operation and which uses only one compartment both for the agitation of the pulp and (by stopping the agitat on and allowing the pulpto become quiet and the floccules to come to the surface) the separation of the pulp may be used It is preferable, however, to use a cont nuous machine of two compartments, one in which the oil-mineral-bubble,flocculation is brought about. by vigorous agitation and another in which the 50 treated pulp is allowed to come to a relatively quiescent condition so that the buoyant floccules may come to the surface of the pulp and be removed, the two compartments belng connected so that there is a constant flow of pulp from the agitation compartment into the separation compartment and back into the agitation compartment in a closed circuit. For commercial operations the latter type of machine would probably be the only type used.

From the foregoing it is clear'that the essential feature of the process is the selective concentration of non-siliceous ore-mineral partlcles in an aqueous pulp into buoyant oil-mineral-bubble floccules and their separation from the remainder of the pulp, which contains the siliceous gangue minerals in a dispersed condition. In order to accomplish this and to secure an 'eflicient concentration it is seemingly necessary:

1. That the minerals to be concentrated be ground relatively fine.

2. That the ore, especially the ganguemineral, be not finely ground with metallic iron grinding parts, or if so ground that the effect so produced be removed before treatmentb the process.

3. T at the oil or oily compound used contain a proportion of a fatty or rosin acid or similar compound either free or combined in an oil.

4. That the oil or oily compound be used in sufficient quantities to prevent the carrying of much of the siliceous gangue-minerals into the concentrates, an approximate minimum amount equal to per cent, more or less, of thu weight of the concentrates.

5. That the agitation of the pulp be '-vio lent enough to break u the oil and air into minute globules and thoroughly mix them with the pulp.

6. That the oil-flocculation be not con: ducted in an acid or alkaline solution.

7. That the ore be not agitated in contact with metallic iron for any considerable period previous to, or while the oil-flocculation is taking place.

8. That the pulp be brought to a state of sufiicient quiescence after the formation of the oil-mineral-bubble floccules that they may come to the surface of the pulp and be removed.

And to secure the best results it is preferred:

1. That the water in the pulp contain no dissolved electrolytes.

2. That the, oil-flocculation be not conducted with a metallic agitating device.

- garnierite, serpentine talc, etc. called the ore-mlnerals in the specifications 3. That essential oils be not used in considerable amount.

Having described the rocess, the action of the difierent minerals is described in the following: As before noted, according to their actlon in my process, the oxidized minerals are separable intogtwo broad classes.

Class I. Minerals which cannot be oilfiocculated but remain in a dis ersed condition in the pul and Class I minerals which can be oilocculated and which may be removed from a pulp by formation of buoyant oil-mineral-bubble floccules as described. To Class I belong all the quartz minerals and all the silicate minerals (except those mentioned in Class-II). These are called the gangue-minerals in the speci fications and claims. To Class II- belong all the non-silicate oxidized minerals and a few silicates such as rhodonite, willemite, These are and claims. Intermediate between the two main classes are a few silicates, which show a slight degree of oil-flocculation, such as some garnets and chrysolites and prehnite Ind sodalite. Fortunately, for the value of the process the important gangueminerals are distinctlyof. the Class I type and the important ore-minerals of the Class II type, and the intermediate class between the two contains very few minerals of'any importance or of frequent occurrence in any considerable percentage in ores. It is of some theoretical interest to note that in general the minerals of Class I are theprimary minerals arid metamorphic minerals which are formed under conditions of relatively extreme-heat and pressureand the minerals of Class II are the non-silicate and silicate minerals which may be and are usually formed by the action of or precipitation from aqueous solutions at ordinary temperatures and some silicates formed by the complete alteration of some of the minerals of Class I by aqueous solutions, and that the 7 small intermediate class consists of minerals formed byconditions intermediate between the two or by the partial alteration of some of the minerals of Class I.

It is also of considerable theoretical im- I the carbonates, sulphates, phosphates, halidles arsenates and chromates, etc. (i. e. chemical salts) oil-flocculate more quickly and the floccules levitate more readilythan the oxides or hydroxides, and the latter oilflocculate more quickly and the floccules levitate more readily than the silicates of this class. Minerals of the'same class also exhibit considerable difference in this respect, for example, azurite oil-flocculates.

more readily and levitates. more uickly than malachite, manganite and bauxite oilflocculate more quickly and the floccules levitate more readily than is the case with hematite and limonite, and rhodonite oilfiocculates and the floccules levitate more quickl than garnierite. possiblia the preferential separation of some of the ore-minerals with a greater or less degree of perfection by the process. For example, in the treatment of an oxidized copper sandstone ore, the first part of the concentrates removed from the pulp was mainly azurite and the last part mainly malachite.

The foregoing statements regarding the action of the oxidized minerals in my process are based on a great number of tests on specimens of all but the rarest minerals and upon samples of numerous oxidized ores of many different kinds.

Sulphide minerals such as galena, etc., act in a manner entirely different to the oxidized ore minerals in my process. 1 For example, if the oil is addedv during the grinding of an ore containing galena, the galena granul-ates or coagulates and forms heavy balls, lumps, or granules, which may be separated from This fact makes the pulp by screening, or by treatment in a.

classifier or on a concentratin-g table but floccules and come to the surface of the pulp I nomenon of the progressive selective rejection of the gangue-minerals from the fioccules can be seen with remarkable clearness by treating a small portion of the low grade oil-mineral fioccules from a larger operation, in a, test tube artially filled with water. By adding ad itional oily agent drop'by drop, and shaking the test tube vigorously the rejection of the gangueminerals and their dispersion in the water is made plainly visible. The fact that all the Silica cannot be rejected is probably due to the fact that the floccule cannot contain or hold enough of the fine air bubbles to neutralize its residual positive charge and this remaining part is neutralized by the floccule taking up silica. If, however, the fioccules are removed from the presence of the gangue-minerals in the pulp and the operation repeated with 'an excess of fine bubbles present, more of the gangue minerals can be rejected. Also if an excess of fine bubbles is injected into the relativelyquiescent pulp during the separation of the fioccules from the pulp, more of the gangue particles may be replaced by air bubbles. But as the fioccules cannot hold enough fine air bubbles to neutralize the residual positive charge, it is theoretically impossible to displace all of the gan As more oil is added, the residual positive charge of the floccule becomes less and less until the number of air bubbles it can hold becomes progressively smaller and the floccules lose buoyancy, and with a large excess of oil may lose their buoyancy entirely. Accordingly to this theory also, if the oil-mineral-bubble fioccules should be gradually' neutralized, i. e. lose the residual positive charge on the ore-mineral by any means after removal from the pulp, they would tend to become dispersed and the gangue particles would be gradually rejected. This does occur when the fioccules are removed from the pulp and settled in. water. Most of the bubbles are lost almost immediately and the silica is gradually dropped. As the discharge of the residual positive charge on the ore mineral continues (probably by leakage through the oil covering) by the long standing in water, the floccules gradually becomes dispersed but this change is resisted by the oil, the surface tension of which tends to hold the oiled minerals together. As noted in the description of. the operation of the process, this does actually take place in practice. 4

The foregoing description of the method of formation of the oil-fioccules explains the great difference in characteristics between the flocks of ordinary flocculation and sedimentation and the oil fioccules. nary flocks are held together onl by the very weak force of mass attraction. gravity) and these flocks are therefore very easily ne particles.

The ordi-.

. menses broken and very loosely held together. The oil flocks are held together not only by this force but by the much stronger forces of the elfictrical charges and surface tension of the o From the above theoretical consideration there should be av rather indefinite theoretical minimum amount of oil for good work and a rather indefinite theoretical amount above which the addition-of oil does no good, and with increasing proportions does harm. The amount of oilused should also theoretically be proportional to the percentage of ore-minerals in the mineral mixture, and should increase somewhat with the fineness of grinding (due to increased surface) and varywith the differing charges carried by different kinds of minerals. The foregoing theoretical requirements are strikingly met by the following facts observed in the practical operation of the process.

1. That the amount of quartz and silicates in the fioccules progressively decreases as the oil is increased. x

2. That, a rather indefinite minimum amount of-oil (proportional to the weight of the minerals to be concentrated) must be used.

3. That, above a similar rather indefinite maximum amount, the additional oil is of no advantage. i

4. That a large excess of oil decreases the buoyancy of the oil-mineral-bubble fioccules.

5. That the amount of oil used to secure similarresu'lts with different ores is proportional to the weight of the concentrates.

6. That the amount of oil increases with the fineness of grinding and is somewhat different with difl'erent ores and difierent oils- 7. That the machines producing the largest amount of the finest bubbles give the best results.

8. That the concentrate can be cleaned by successive treatments, the more fine bubbles present the better the cleaning.

9. That some of the fine silica can be washed out of the fioccules after their re-' moval and settlement .in water.

10. That the finest part of the ganguematerial remains in the fioccules.

The theory of the action of the metallic iron is asfollows:

During the grinding operation (or during the abrasion of the iron by violet agitation of the pulp in the presence of the iron) 'minute particles of iron are rubbed off the grinding parts. As these particles are positively charged they are constantly attracted by the fine gangue particles andthe finer gangue particles i. e. quartz and silicates are especially attracted by the iron particles which carry a relatively large charge. The very fine iron is quickly oxidized and, as the iron and gangue partlcles lot are continually attracted to each other, a large part of this oxidation takes place when the iron and silica are in contact and results in the coating of the silica with a fine film of iron oxide. As the charge is entirely on the surface of a particle, these coated gangue particles are now positively charged and enter the floccules in the same way as the ore minerals. This theory is borne out by the fact that the gangue-minerals which are rendered oil-flocculahle by grinding or scouring with iron ore are in every case colored a tan color in the grinding or scouring process. The shade of this coloration will vary from a very faint tinge to a deep tan or brown, according to the time of contact orgrinding, and the amount of iron surface exposed to scouring or grinding. The gangue-particles rendered oil-flocculable by this treatment with iron according to this theory should act in a manner similar to the ore minerals in every respect, not only in being oil-flocculated but also with respect to the effect of acids, alkalis .and other eleclrolytes which is found tobe the case in .practical operation. The removal of this efi'ect of the iron on the quartz and silicates by treatment with acid consists in the (llS- solving or removing of this thin iron oxide coating, and thus restoring these gangue minerals to their ,uncoated condition in V which condition they are negatively charged.

The reason that the residual acid from this acid treatment should be neutralized with limestone rather than an alkali is that the iron oxide precipitated by the alkali tends to recoat the particles of quartz and silicates. It is also much easier to secure a neutral solution by using the limestone.

The theoretical explanation of the efiect of fine metallic (unoxidize'd) iron (or other metal) in the pulp is that the metallic iron particles carry relatively very large positive charges. The metallic iron particles are wet by the oil and enter the floccules with the ore-minerals, thus giving the fioccules a relatively very large positive charge. As the efi'ectof this charge cannot be neutralized with .air bubbles owing to the limited capacity of the flocculcs to hold these, the effect of this additionally large charge must be neutralized by the gangue-mineral particles, thus bringing more gangue mineral into the fiocc-ules. Theoretically this effect should be proportional to the amount of iron and would be small-with very small amounts of iron. This is shown to be the case mall the tests made on this point as previously noted. This eiiect is very much smaller in practical operation than the previously described eflect when the iron is oxidized and coats the gangue -mineral particles. The theory of the action of the iron explains the very poor results secured in an iron ma chine. It also explains the slightly better minerals to be concentrated',must be finely ground in order that the mass .of each of the particles be not too large in proportion to its surface as the latter determines the amount of charge that the particles can carry. The fineness of grinding necessary should also vary with thediflerent minerals according to the capacity of the surface of the particles of these to hold an electrical charge. Practical experience with the process is in strict accord with this theory, those minerals which have the greatest capacity for taking-a charge requirin the least reduction in size. The minera s which have this capacity in a greater degree are those which are the most crystalline and whose cleavage "Faces come nearest to a metallic lustre. This is most strikingly borne out by the preferential action of the process on dif forent ore-minerals, for example,'with azurite and malachite.

According to the electrical theory only those oils would be useful in my process which are practically insoluble in water, and

which can be broken'u into minute globules in the water, and t us become charged. This is strikingly confirmed by considering the oils which are useful in the process, and explains the deleterious effect of soluble oils, which tend to dissolve the insoluble oils'and make them more soluble. This also partially explains the fact that the essential oils are not useful in the process. These oils are partially soluble and do not break up into globules but surround the air bubbles andtherefore act in an entirely different manner to the other types of oils, su'ch.as the fixed oils. and the rosin mixtures.

According to the electrical theory, the finer bubbleswould be much more active in the process which is in strict accordance with practical results.

' The theoretical explanation of the efiec't lot of acidis twofold- First, the acid dis-- globules due to the action of the surface tension of the oil. This latter effect is instantly shown when acid is added to water in which the oil has been dispersed. The dispersion is immediately destroyed and larger globules of oil formed.

The theory of the action of the alkali is also two-fold. First the alkali increases the charges on the particles and gives all the particles in the pulp the same kind of charge, greatly increasing the dispersion and entirely preventing any flocculation. Second, the alkali acts on and dissolves the oil making a soluble compound which prevents dispersion of the oil into globules of the character necessary in the process. The oil loses its power of dispersion into globules and instead coats the fine air bubbles in a manner similar to the essential oils forming a mass of white foam which has no action on the minerals in the deflocculated pulp. The action of soap which is alkaline is similar to that of the alkalis.

The theory of the action of the neutral electrolytes is that the addition of the salt first entirely discharges the mineral particles. The mass attraction between the particles then causes them to floculate nonselectively. When the Oil is added to a pulp in this condition, the non-selective flocks are first oil-flocculated as such, and this action is entirely nonselective. As 1t is only the mass attraction, WlllCh'lS relatively very weak, which holds the excess gangue particles in the oil-floccules these particles are soon'displaced by a vigorous agitation and remain in a relatively dispersed condition, as compared with theoil floccules, though in a flocculated condltion, in the pulp. When the pulp becomes quietthese gangue particles settle out in flocks of the ordinary kind such as occur in ordinary settlement or sedimentation. This shoivs clearly that ordinary flocculation and the selective oil-flocculation of my process are entirely distinct and separate phenomena. Ac ording to this theory, only the neutral salts which flocculate the pulp would have the effect described. This is found to be the case, some electrolytes being helpful in the process.

According to the foregoing theory the fine particles of siliceous gangue-material remaining in the-pulp after the removal of the concentrates should be left in a relatively highly dispersed condition as these particles are all negatively charged and tend to repel each other and remain dispersed. In practice this is found to be the case. The tailings solutions from the flotation cells remain milky for a considerable period, and it is practically impossible to settle or filter them without adding acid to discharge these negatively charged particles. The action of the fine particles of tailings is in menace marked contrast to the quick settling of the finely ground ores which usually settle quite rapidly, but this is also in accord with the foregoing theory as, unless the particles of gangue and ore-mineral are kept in constant agitation (when there would be a constantly recurring charging and neutralizing of the ore and gangue-particles by each other) their opposite charges should neutralize eachother, and the pulp should flocculate more or less rapidly and settle quickly. This is found to be the ease in practice, the finely ground ores which contain the two classes of minerals in .nearly equal proportions settle much more quickly than ores containing very unequal proportions of the two classes of minerals. The ores ground with iron also settle much more slowly than those ground with quartz pebbles, which should be the case according to the theory, since in the iron grinding operation the gangue particles are changed so as to all carry positive instead of negative charges, and therefore all the particles in the pulp being similarly chargedshould repel each other, remain dispersed, and settle slowly.

The theory of selective oiling of the oremineral particles is as follows: @The wetting or oiling of the ore-mineral particles is not intrinsically due to the opposite charges of the particles of the two, since the ganguemmeral particles in the floccules have the same chance as the oreminerals of being I oiled. There is, however, a selective oiling of the ore-minerals in the presence of the gangue-minerals. At the root of this action is a chemical or quasi-chemical reaction or tendency to chemical action between an ingredient of the oil and the oreminerals. That this is the case is indicated by the fact that only those oils which contain a fatty or rosin acid, or analogous compound are active in the process. The fatty acids do form compounds with the bases which (other than those with the alkalis) are relatively insoluble in Water, but are relatively more soluble in the oil or 011 compound. The theory of the selective oiling 'is then that the acid constituent of 1 the oil acts superficially upon the surface of the ore-mineral, and either forms a compound which is-more soluble in the oil than in water, or due to this chemical tendency causes the adsorption of the oil or a constituent thereof at the surface of these particles and thereby causes these minerals to be preferentially wet by the oil.

According to this theory, the minerals which are acted upon with difficulty by chemical reagents would not be oiled while those minerals which are easily acted upon by chemical reagents are oiled. This corre-- sponds with the fact that the process is especially applied to the separation of the -minerals which as a class are not acted upon by ordinarychemical reagents, i. e., are relatively insoluble, from those which as a class are relatively easily acted upon by chemical reagents, i. e., are relatively soluble. According to this theory,'the oils. would tend to wet only those minerals which contain a base with which the acid component of the ore could form a compound. This corresponds with the fact that no form of mineral composed of SiO. is wet by the oil. According to this theory only those oils which would have a tendency to act chemically upon the ore-minerals would oil the ore-minerals which explains why the essential oils and mineral oils, which are neutral hydrocarbons, do not oil these minerals.

Also according to this theory, since this quasi-chemimil reaction, chemical reaction or chemical tendency is relatively weak, its

effect is destroyed unless the conditions are favorable and therefore such strong factors as the effect of acids and alkalis destroy the operation of this force.

According to this theory the rapidity of oiling should be differentwith different minerals, and the more insoluble should take the longer time for oiling. This is found to be the case in practice almost without exception, for example the few silicate ore minerals, which are more or less insoluble, require a considerable period of mixing in order to be oiled and oil-floz-culated. According to this theory there would be no sharp break between the two classes of minerals which are separated by my process but the two classes would be joined by minerals having characteristics intermediate between the two as to solubility. As before noted this is found to be the case in testing out the different 'minerals and ores. 7

From the foregoing it is readily seen that my process is not an entirely empirical process but is based upon a well substantiated scientific theory which is a valuable guide to the investigation of each step in the process and to the investigation of the oils which can be used and 'the ores or minerals whi h can be treated, and makes possible the understanding of unusual phenomena occurring in the practical operation of the process and suggests the remedies for the conditions which cause these phenomena.

This theory is a generalization drawn from a very large amount of research work and observation extending over a consider able period of time, and is strikingly verified by all the phenomena of the practical opera tion of the process.

It is to be understood, however, that while I believe the exposition of the theory.

as above outlined is correct, that I do not desire to be limited thereby, and the same is given merely to elucidate and make clear the application whi h is open to my process;

13 i The greatetficienc by the following y reports-on tests of a few widely dltferent.

of my process is shown A manganese ore-consisting mainly of manganite in a porphyry' gangue:

Weight. Mii. inedible Heads 100 30.1 Concentrates... 47 60.3 .II..I.III 'lailings 53 as 5 Recovery 94 High grade-copper carbonate ore in sandstone: 7

a Weight. Cu. SiO

Heads 12.3 i 76 Concentrates 45. 6 13. 2 'lailings.... 0. a one Recovery... 98.0 i

Oxidized lead ore in silicified limestone:

Assay.

7 Oz. Oz. 57 '7 '7 wt. Au. Ag. Pb. 08. cab. F3. S1431 Heads 100 .025 17.2 1L8 l 4.6 3.3 65.6 Concentrates 35 -07 45. 3 32. 6 3 11. 5 7. 9 l2. 2 Taihugs 65 Trace. 2.2 .2 Tr. .8 .5 95.1 Recovery 95 91. 5 98. 6 95 89. 7 83. R

Low grade copper carbonate ore in sandstone:

% Wt. Cu sio,

mam... "100 2.1 Concentrates. 5. 1 38. 6 31 MiddlinIZS 6 2. 4 R2. 9 'lailings 88.9 .10 90.1 Recovery 94 A large number of tests on many different kindsof ores show resultsof the same character as the foregoing. Oxidized ores of copper, lead, Zing-manganese and ores carrymg oxidized minerals of value such as carnotlte, etc., 1n different slliceous'gangues are amenable to treatment with excellent re-' sults. As it is obviously impossible to give the many small variations possible in the commercial application of my process in the scope of a patent application I desire to be limited only by the appended claims as interpreted in the light of the foregoing specifications.

This application is a continuation in part of my pplication Serial No. 230,792, filed as of April 25, 1918. I

What is claimed is:

1. The art of concentratingna-tural oxidized ores, i. e. unaltered except by grinding, which consists in forming with such oxidized ores in comminuted form an aqueous pulp free from electrolytes which inhibit the selective formation of oil-mineral floccules 7 containing ncn silicmns-minerals, an

oily mhetancs, snbstantialiy ins'o-iuhie 351 water, eontaina g an organic acid radical preparation to form oil-mineral fioccuies which the non-siliceous minerals oi the ore a concentrated, agitating the; said mixture.

and; separating the floccules thereby formed from the, remainder of the pulp containing the siliceous minerals of the ore.

2. The art of concentrating natural oxi-r di zed ores, i.- e. unaltered except by grinding, which consists in forming with suchv oxidized ores 1n comminuted form an aqueous pulp free from electrolytes which inhibit the selective formation of oil-mineral floccules containing- -non'-.siliceous minerals, adding an oily substance, substantially'insolubleiin watencontaining an organic acid radical in} proportion'to form oil-mineral floccules in which the non-siliceous minerals of theore" are concentrated, agitating the said, mixture and-separating the fioccules thereby formed 3.-'The art of concentrating natural oxi-. diz'ed ores, i. e. unaltered except by grinding,

' which consists in forming with such oxidized containing non-siliceous minerals, adding an ores in comminutedjorm'an aqueous pulp such, 1. e.'una1tered otherwise than by grindfree-fro'm electrolytes which inhibit the selective formation of oil-mineral floccules oily substance, substantially insoluble in water, containing an organic acidaradical in proportion to form oil-mineral floccules-in which the non-siliceous minerals of the ore are concentrated, agitatingand aerating the r said mixture whereby the non-siliceous minerals are selectively oiled and forming a buoyant fiocculent froth and separating the froththereby formed from the remainder of i the pulp "containing the siliceous minerals of the ore.

4:. The art of concentratingjnaturaloxi- 4 dized ores, i. e. unaltered except-by grinding, which consists in forming with such-oxidized ores incomminuted form an aqueous pulp free from electrolytes which inhibit the se- ,lective "formation of oil-mineral floccules containing non-siliceous minerals, adding an oily substance, substantially insoluble in water, containing anorganic acid radical in proportion to form oil-mineral-floccules in which the nones'iliceous minerals. of the ore are concentrated,agitating the said mixture substantially without contact with metallic iron and separating the floccules thereby formed from the. remainder of the pulp containingthe siliceous minerals of the ore.

5. The. process of treating oxidized ores as such, -i. e. unaltered otherwise than by grinding, which consists in finely grinding the ore with siliceous grinding-media, forming'with the-finely ground ore-an-aqueous from electrolytes which inhibit the selective formation of oil mineral floc water, organic acid rsgdioai' preparation cc term oil-mineraifioccules which daemon-siliceous minerals oi thevore.

are concentrated, and agitating said mixture and separating the fioccules thus iormed from the'residue of pulp containing the si- 1 liceos minerals of the ore.

6. e process of treat-mg oxidized ores,

pulp free from'electrolytes which inhibit the 1'5 a's su :h,-,i. e. unaltered otherwise than by grinding, which consists in finely grinding selective formation of oil mineral floccules containing non-siliceous minerals, adding an oily agent substantially insoluble in water; containing an organic acid radical in proportion to form oil-mineral vfioccules in which the'non-siliceous minerals of the ore are concentrated, and agitating and aerating said mixture whereby the non-siliceousminerals are selectively oiled and fornia buoy ant flocculent froth and separating the froth thus formed from the residue of pulp containing the siliceous minerals of the ore.

7 Theprocess'of treating oxidized ores as ing, which consists in finely grinding the ore-with siliceous grinding media, forming v with the finely ground ore an aqueous pulp free from electrolytes which inhibitthe selective formation of oil mineral floccules containing non-siliceous minerals, adding an oily agent substantially insoluble in water, containing an organic acid radical in,

proportion to form oil-mineral floccules in which the'non-siliceous minerals of the ore 8. The process of treating oxidized ores as such, i.-e. unaltered otherwise than by grinding, which consists in finelygrinding the ore with siliceous grinding media, formingwith the comminuted ore an aqueous pulp free i from electrolytes which inhibit'the selectiveformation of oil-mineral floccules containing non-siliceous minerals, adding'an oily agent, substantially insoluble in water, containing an organic acid radical, in a proportion equal to approximately ten to fifteen per cent of the weight of the non-siliceous minerals of the ore, and agitating and aerating said mixture whereby the non-siliceous mmerals-are selectlvely oiled and form a. buoys ant flocculent froth, and separating saidfroth from the remainder of the pulp containing the siliceous gangue minerals of the ore.

containing an organic acid radical, 111 a ro-,

portion equal to approximately ten to fi teen per cent of the weight of the non-siliceous minerals of the ore, and agitating and aerating said mixture substantially without con tact with metallic iron whereby the nonsiliceous minerals are selectively oiled and form a buoyant flocculent froth, and separating said froth from the remainder of the pulp containing the siliceous gangue minerals of the ore.

10. The process of treating oxidized ores as such, i. e. unaltered otherwise than by grinding, which consists in finely grinding the ore with siliceous grinding media, forming with the comminuted ore a neutral aqueous pulp, mixing with said pulp an oily agent which will selectively 011 the nonsiliceous minerals in a proportion approximately ten to fifteen per cent of the weight of the non-siliceous minerals of the ore, and agitating and aerating said mixture whereby the non-siliceous minerals are selectively oiled and concentrated into buoyant flocculent froth, and separating said froth from the remainder of the pulp containing the siliceous gangue minerals of the ore.

11. The process of treating oxidized ores as such, i. e. unaltered otherwise than by grinding, which consists in finely grinding the ore with siliceous grinding meda, forming with the comminuted ore a neutral aqueous ulp mixing with said pulp an oily iiich will selectively oil the none. siliceous minerals in a proportion approxiagent w mately ten to fifteen per cent of the weight of the non-siliceous minerals of the ore, and agitating and aerating said mixture substantially without contact with metallic iron whereby the non-siliceous minerals are selectively oiled and concentrated into buoyant flocculent froth, and separating said froth from the remainder of the pulp containing the siliceous gangue minerals of the ore.

12. The process of treating oxidized ores as such, i. e. unaltered otherwise than by grinding, which consists in finely grinding substantially without contact with metallic iron, forming with the finely ground ore an aqueous pulp free from electrolytes which inhibit the selective formation of oil min-.

eral floccules containing non-siliceous minerals, adding an oily agent substantially inof the ore are concentrated, and agitating said mixture and separating the floccules thus formed from the residue of pulp containing the siliceous minerals of the ore.

13. The process of treating oxidized ores as such, i. e. unaltered otherwise than by grinding, which consists in finely grinding substantially without contact with metallic iron, forming with the finely ground are an aqueous pulp'free from electrolytes which inhibit the selective formation of oil mineral floccules containing non-siliceous minerals, adding an oily agent, substantially insoluble in water containing an organic acid radical in proportion to form oil-mineral floccules in which the non-siliceous minerals of the ore are concentrated, and agitating and aerating said mixture whereby the non-" siliceous minerals are selectively oiled and form a buoyant flocculent froth and separat ing the froth thus formed from theresidue of pulp containing the siliceous minerals of the ore.

14. The process of treating oxidized ores as such, i. e. unaltered otherwise than by grinding, which consists in finely grinding substantially without contact with metallic iron, forming with the finely ground ore an aqueous pulp free from electrolytes which inhibit the selective formation of oil-mineral floccules containing non-siliceous minerals, adding an oily agent substantially insoluble in Water, containing an organic acid radical in proportion to form oil-mineral floccules in which the non-siliceous minerals of the ore are concentrated, and agitatinn and aerating said mixture substantially without contact with metallic iron whereby the non-siliceous minerals are selectively oiled'and form a buoyant flocculentfroth and separating the froth thus formed from the reside of pulp containing the siliceous minerals of the ore. r.

15. The process of treating oxidized ores as such, i. e. unaltered otherwise than by grinding, which consistswin finely grinding substantially without contact with metallic iron, forming with the comminuted ore an aqueous pulp free from electrolytes which inhibit the selective formation of oil-mineral floccules containing non-siliceous minerals, adding an oily agent, substantially insoluble in water containing an organic acid radical, in a proportion equal to approximately ten to fifteen per cent of the weight of the nonsiliceous minerals of the ore, and agitating and aerating said mixture whereby the non-siliceous minerals are selectively oiled and form a buoyant flocculent froth, and separating said froth from theremainder of the pulp containing the siliceous gangue minerals of the ore.

16. The process of treating oxidized ores as such, 'i. e. unaltered otherwise thanby grinding, which consists finely grinding 'substtially withont contact with metallic iron, fog with the comminuted ore an seasons pulp free from electrols' which inhibit the selective formation ofoil-mineral floccules containing non-siliceous minerals, adding an oily agent, substantially grinding, substantially without contact with metallic insoluble in water containing an organic-acid radical, i a proportion equal to approximately ten to fifteen per cent of the weight of the non-siliceous minerals of the ore, and

agitating and aerating said mixture substantially without contact with metallic iron whereby the non-siliceous minerals are se lecti-vely oiled and form abuoyant flocculent froth, and separating said froth from the remainder of the pulp containing thesiliceous gangue minerals of the ore.

17. The process of treating oxidized ores as such, i. e. unaltered otherwise than by which consists in finely grinding iron, forming withv the comminuted ore a 4 neutral aqueous pulp, mixing with said pulp of the non-siliceous minerals of the ore, and

an oily agent which will selectively oil the non-siliceous minerals in a proportion approximately ten to fifteen per cent of the weight of the non-siliceous minerals of the ore, and agitating and aerating said mixture whereby the non-siliceous minerals are selectively oiled and concentrated into buoyant flocculent froth, and separating said froth from-the remainder of the pulp containing the siliceous gangue minerals of the ore. 1

18. The process of treating oxidized ores 'as such, ire. unaltered otherwise than by grinding, which consists in finely grinding substantially without contact with metallic iron, forming with the comminuted ore a neutral aqueous pulp, mixing with said pulp an oily agent which will selectively oil the nonsiliceous minerals in a proportion approximately ten to fifteen per cent of the weight which inhibit the selective formation of oill floccules containing non-siliceous minerals,

mixing with said pulp an oily agent which will selectively oil the non-silicate minerals and leave the siliceous gangue minerals unoiled, and agitating said mixture, and dur-' ing with the finely aneaaaa a ingthepuction and treatment efithe pulp. I maintaining the same out of contact with metallic iron surfaces whereby the non-silicate mineralsare selectively oiled and form a buoyant flocculent froth, and separating said froth from the remainder of thepulp containing the siliceous gangne minerals.

Q0. ihe process of treating'oxidized ores as such, i. e. unaltered otherwise than by grinding, which consists in finely grinding the ore with siliceous grinding media, formaqueous pulp containing in solution no acids, alkalis, acid salts or alkaline salts, in sufiicient quantity to give any other than aneutral reaction to the pulp, mixing with said ground ore a neutral pulp an oily agent which will selectively oil 89 the non-siliceous mineral particles and will leave the siliceous minerals unoiled, and agitating and aerating said mixture without sufiicientcontact with metallic iron to destroy the selective action of the oil, whereby the non-siliceous minerals are selectively oiled and form a buoyant flocculent froth, and separating said froth from the remainder' of the pulp containing the siliceous gangue mineral particles ofthe ore.

21. The process of treating oxidized ores as such, i. e., unaltered otherwise than by grinding, which consists in finely grinding the ore with siliceous grinding medla, forming with the finely ground ore a neutral aqueous pulp, mixing with said pulp an oily agent which will selectively oil the non-silicate minerals and leave the siliceous gangue minerals unoiled, and agitating and aerating said mixture without appreciable contact with metallic iron, whereby the non-silicate minerals are selectively oiled and form a buoyant flocculent froth, and separating said froth from the remainder of the pulp containing the siliceous gangue minerals.

' 22-. The process of treating oxidized ores, as such, which consists in finely grinding the ore out of contact with metallic iron media; forming with the finely ground ore a neutral aqueous pulp; mixing with said pulp an oily agent which will selectively oil the non-silicate minerals and leave the siliceous gangue minerals unoiled; and agitatingand aerating said mixture, and during-the production and treatment of the pulp maintaining the'same out of contact with metallic 4 iron surfaces, whereby the nonsilicate mine'rals are selectively oiled and form a buoy [ant flocculent froth; and finally separating 'said froth from the remainder of the -ulp containing the siliceous gangue mineral;

In testimony whereof I have signed my name to this specification.

'NIELS CHRISTENSEN.

. \Vitness:

I THEODORE Smnnms, 

